The present invention is particularly applicable but not necessarily limited to the conveyance of thin-walled metallic containers of the general type which are in widespread use for packaging various foodstuffs including beverages or the like which in a preliminary stage of their processing, include a longitudinally extending circular side wall having a closed bottom and an open top. While containers of the foregoing type may be comprised of any one of a variety of materials providing for a thin-walled resilient construction, such as, for example, various plastic materials, tin-plated steel, plastic-lined steel and aluminium; of the foregoing, aluminum containers produced by the deep drawing, or a draw and redraw, or a draw and ironing, of an aluminium blank are perhaps the most common and are receiving increased acceptance. Modern automatic machines have been developed for deep drawing aluminum and steel container bodies in a single operation at high rates of speed up to about 200 container bodies per minute, which after the forming operation are trimmed along their open edge and are thereafter subjected to various cleaning and coating operations prior to entering the filling operation. After the container is filled, a suitable top is affixed conventionally having a tear-tab opener.
Various techniques have heretofore been used or proposed for transporting or conveying the preliminarily-formed containr bodies from the forming step through various treating steps to the filling operation. An apparatus and method for effecting a high-speed treatment of the surfaces of such container bodies is disclosed in U.S. Pat. Nos. 3,704,685 and 3,748,177, which are owned by the same assignee as the present invention. In accordance with the teachings of the aforementioned United States patents, longitudinally-extending guide rods are provided for supporting the workpieces as they are propelled therealong in longitudinally spaced end-to-end relationship and the workpieces, such as containers, are subjected to a plural liquid treatment by the impingement of high pressure liquid streams against the inner and outer surfaces thereof. The treatments may conventionally comprise a cleaning treatment to effect the removal of contaiminating substances such as die lubricants from the exterior and interior surfaces of the container bodies and the application of a chemical conversion coating, such as a chromate coating, to the cleaned surfaces improving the resistance of the container to chemical attack and also rendering the surface more receptive to overlying decorative coatings such as a paint, for example, to provide the desired decorative appearance.
Following the treatment of the container bodies, the cup-shaped containers are transferred by various conveying systems to the filler apparatus. A vortex diffuser air rail conveyor as described in U.S. Pat. No. 3,782,791 has been employed for supporting the container body on a cushion of air, minimizing friction and enabling enAbling a setting or drying of the coated surfaces to an extent that the container bodies can be handled without a marring or damage to the coatings thereon.
The high velocity of such container bodies at relatively close spacing intervals during their conveyance on an air rail of the type disclosed in the aforementioned U.S. Pat. No. 3,782,791 has occasioned contact in some instances between the leading and trailing edges of adjacent containers which has occasioned disruptions in the uniform conveyance thereof. Some difficulty has also been encountered in providing a uniform spacing between adjacent containers to enable an orderly transfer of the containers from the air conveyor rail to transfer equipment adjacent to the outlet end thereof.
In accordance with the discovery comprising the present invention, the problems heretofore encountered in connection with the high speed conveyance of containers is overcome, maintaining a substantially uniform spacing between adjacent containers and resisting mutual impact therebetween, avoiding thereby damage to the container and the treated surfaces thereof while further improving the orderly transfer of the containers from the conveyor rail to associated transfer equipment.